1. Field of the Invention
The present invention relates to rotary drill bits including hard wear resistant inserts. More particularly, the present invention relates to the geometry of inserts finding application in rotary drill bits and a method of use.
2. Description of the Related Art
Rotary drill bits are typically attached to a working end of an elongated, hollow drill rod having an opposing end connected to a source of rotary and thrust power. By the action of the source of rotary and thrust power, rotary drill bits may be used for drilling holes in a work surface such as a rock strata in the roof of a mine entry for installing roof bolts or receiving explosive charges. Rotary drill bits which are secured to the working end of the drill rod include a body having a top working surface to which is attached at least one insert made of a hard wear resistant material.
It will be appreciated that the speed with which holes can be drilled, the maintenance of the penetration rate, and the wear and fracture resistance of the inserts used in rotary drill bits are important factors in drilling a work surface. Furthermore, the inserts which may be used in the rotary drill bits must be capable of resisting wear, fracture, and the abrasive action of the chips from the work surface being drilled. Improvements in any of these factors is desirable, and has to some degree been achieved by changing the composition of the insert material, usually a cemented carbide, by adjusting the carbide grain size, or by changing the insert geometry.
The present invention relates to improved insert geometries finding application in rotary drill bits and a method of use of the rotary drill bits.
Examples of various insert geometries may be found in U.S. Pat. Nos. 4,489,796; 4,527,638; 4,342,368; and 4,787,464. Although, the variations in insert geometries heretofore known have improved some or all of the above factors, it will be appreciated that there is still a significant need for improved insert geometries.